耦合燃煤机组的水泥窑余热利用系统热力学性能分析

Thermomechanical performance analysis for waste heat recovery and utilization system of cement kiln coupled with coal-fired power plant

提出了一种更高效的耦合燃煤机组的水泥窑余热回收利用系统,采用水泥窑炉排冷却器排出空气和旋风预热器废气的热量加热燃煤机组的部分凝结水,从而节省汽轮机抽汽,增加汽轮机做功,同时根据热力学第一和第二定律分析余热利用系统性能提升的原因。结果表明:耦合燃煤机组后水泥窑余热利用系统效率显著提升,机组发电量得到提高;与常规水泥窑余热利用系统相比,所提出余热利用系统可增加6.83 MW净发电功率;此外,余热利用系统的发电效率和净热效率提高了18.25百分点和8.17百分点;系统发电(火用)效率和总(火用)效率分别提升了39.37百分点和29.24百分点。经济分析表明,所提出余热利用系统省去了部分设备,投资成本低,回收周期短,净现值高,经济优势明显。

An advanced cement kiln waste heat recovery system(WHRS) coupled with coal-fired power plant is proposed.The heat of the exhaust from clinker cooler and the waste gas of cyclone preheater is used to heat part of the feedwater of coal-fired power plant,thereby saving steam extraction from the turbine and increasing the steam turbine work.According to the first and second laws of thermodynamics,the reasons for the waste heat utilization system performance improvement are analyzed.The results show that,the coupled system increases the power generation and significantly improves the efficiency of the waste heat recovery system.Compared with the conventional cement plants waste heat recovery system,the proposed waste heat recovery system can increase the net power generation by 6.83 MW.Moreover,the power generation efficiency and net thermal efficiency of the system increases by 18.25 percentage points and 8.17 percentage points,and the power generation exergy efficiency and total exergy efficiency of the system increases by 39.37 percentage points and 29.24 percentage points,respectively.Economic analysis shows that the proposed waste heat recovery system saves part of the equipment,has low investment cost,short recovery period,high net present value and obvious economic advantages.